In Reply: Dr Bostom cites data from 2 small studies1,2 published after the submission of our manuscript; 1 is available only in abstract form and was coauthored by one of our coauthors.1 The reductions in homocysteine levels reported in these 2 studies fall within the range of values covered by our sensitivity analyses and would not change any of our conclusions. The intervention in the study of Title et al2 did not include cyanocobalamin, yet it reported a 1.2 µmol/L drop in the homocysteine level from folic acid alone. We would expect an additional 0.8 µmol/L decrease in the homocysteine level if cyanocobalamin were added to the vitamin supplement.3 Indeed, the data from the study of Bostom et al found no additional benefit from folic acid in patients with low homocysteine levels but a significant 1.2 µmol/L decrease when cyanocobalamin was given.1 Much of the residual benefit from vitamin supplementation after folic acid fortification would accrue to people who consume little fortified grain and still have high homocysteine levels. Such individuals may receive a larger benefit than we have modeled.